The open enrolment period for purchasing health insurance on the government-run exchanges is officially over, sort of.

Monday evening, White House officials began leaking news that the total number of Americans insured through the federal and state-run insurance marketplaces could break seven million. That's been perceived to be a "magic number", as it was the mark that the nonpartisan Congressional Budget Office (CBO) predicted enrolment would reach prior to the much-derided launch of the healthcare websites last October.

According to a Los Angeles Times report by Noam N Levey on Sunday, 9.5 million previously uninsured Americans will have acquired coverage under the new system.

Levey writes that the number shows "substantial progress toward one of the law's principal goals and is the most significant expansion since the creation of Medicare and Medicaid in 1965".

This is an outstanding number any way you slice itCharles Gaba, ACASignups.net

The news was greeted with considerable fanfare on the left, which has been yearning for good news on implementation of the Affordable Care Act. Thanks to the law's rocky start, Democrats feared that Republicans would bludgeon their candidates on the issue in the upcoming congressional elections. Now, at last, they see a glimmer of hope.

Healthcare analyst Charles Gaba on his blog ACASignups.net writes on what the latest government numbers mean:

In spite of everything - the terrible website launch of HC.gov and some of the state sites; the still-terrible status of some of the state sites even now; the actively hostile opposition and obstructive actions in certain states, the negative spin on every development by some in the news media - in spite of all of this, over seven million people nationwide enrolled in private, ACA-compliant healthcare plans between 12:01am on 10/1/13 and 11:59pm on 3/31/14 ... slightly surpassing the original CBO projection for that period.

He adds, "This is an outstanding number any way you slice it."

The latest figures could "at least temporarily change the narrative surrounding the law as the media focuses more on success stories than glitches and website blackouts", writes US News's Robert Schlesinger.

Salon's Joan Walsh takes the opportunity to jab doomsayers on her own side, via Twitter: "I wonder if liberals who shrieked about the early ACA 'disaster' will say they were wrong, and talk about why."

If the left is going to successfully defend the Affordable Care Act, argues Sally Kohn on CNN.com, they will have to convince the entire American public of its benefits, not just the 7 million Americans who have signed up on the exchanges.

She writes:

As more Americans access private health insurance choices through the exchange marketplace, receive care minus the discrimination and dirty tricks that insurance companies could get away with in the past, we'll see more people getting the medicine they need, screened for cancer sooner in more treatable stages and pay less for good care.

The real battle is going to be fought over the next few election cycles, as both sides mobilize their coalitionsJay Cost, The Weekly Standard

Conservatives counter that the Obama administration is "cooking the books", in the words of Wyoming Senator John Barrasso.

According to the Washington Post's Marc A Thiessen, there's a big problem with Mr Obama's new health care numbers. The administration hasn't revealed how many of the seven million exchange enrolees have actually paid their first bill.

"It's like putting merchandise in your Amazon cart but never clicking 'buy,'" he writes.

While the seven million figure is a "marketing coup" for Mr Obama, writes Bloomberg View's Megan McArdle, there are still too many unknowns to reach a conclusion about whether the law is working - including how many of that number already had insurance under old system.

Jay Cost of the Weekly Standard says that while some Americans may be benefitting from the Affordable Care Act, thanks to government subsidies and the like, there's a group of "clear losers" who are unhappy with their situation:

Losers in the schema include people whose new insurance is more expensive or otherwise less satisfactory because of the new regulations, seniors whose Medicare Advantage program will be peeled back (or whose local hospital stops taking them because of cuts to Part A), businesses who cannot afford the mandates, people who lose their employer insurance as a consequence of the new business mandates, young and health people, and others.

While Democrats may be cheering now, he says, the contest is far from over.

"The real battle is going to be fought over the next few election cycles, as both sides mobilise their coalitions," he writes. "Republicans must mobilise the losers and also present an appealing counter-offer to the winners."

Given that the battle over healthcare reform didn't end when the bill first passed, nor when Republicans won control of the House of Representatives in 2010, nor when Mr Obama was re-elected in 2012, Cost's assertion that the fight will go on is probably one thing on which both left and right can agree.